@mixin viewport($width: 1024px, $margin: 25px)
  max-width: $width
  margin: $margin auto
  @content

@mixin shadow($opacity: 0.17)
  box-shadow: 0 0 3rem rgba(0,0,0,$opacity)
  &:hover
    box-shadow: 0 0 5rem rgba(0,0,0, (1.5 * $opacity))
